Power transmission systems using gas or liquids under pressure to operate valves, levers, etc. need precisely operating valves to control the pressurized fluid. A typical example is the clutch operation mechanism of a highway truck. The foot pedal is depressed by the driver when disengaging the clutch in order to shift gears, and in modern trucks this operation is usually accomplished by providing a booster or power assisting mechanism to provide the substantial force necessary to operate the clutch while requiring only a small part of that force to come from the driver's foot. The booster or power assisting mechanisms usually employ high pressure air or oil controller by flowing through throttling valves that open and close so as to prevent any sudden surges or cut-offs of the high pressure fluid. Such valves are useful in almost any type of fluid operated equipment. In the prior art it is known generally to employ spool valves for this service, as shown in U.S. Pat. Nos. 3,511,276; 3,542,075; and 3,554,235. The present invention relates to an improved spool valve of the same general type as these.
It is an object of this invention to provide an improved spool valve for use with high pressure fluids. It is another object of this invention to provide an improved spool valve that provides good throttling capabilities. It is still another object of this invention to provide an improved spool valve with surge dampening characteristics. Still other objects will become apparent from the more detailed description which follows.